1. Field of the Invention
This invention generally relates to power supplies, and more particularly, to a system which is capable of providing a short circuit to a power management system during power system reliability testing.
2. Description of the Related Art
The growing demand for electronics and data processing systems is making it increasingly necessary for the electronics and data processing systems to be mass produced in large numbers. Typically, where the systems are mass produced, there exists a concern for making certain that the systems perform within accepted design parameters. One important aspect of the performance evaluation involves determining whether the system power supply will perform reliably when placed in the working environment (e.g. under load, or field conditions).
One particular test known as a xe2x80x9cshort circuit testxe2x80x9d is commonly performed on the power supply prior to leaving the manufacture. The test is used to determine whether the power supply system demonstrates the intended behavior when a short is applied to the power supply for a significant amount of time (e.g., typically, up to about ten milliseconds). By performing the test, a power supply manufacturer is given ample opportunity to gather information pertaining to the operation of the power supply or system application, such as, for example, the trip time of the supply, the maximum (peak) current or voltage during the test, the behavior of the system application or the overall performance of the power supply management system. Where the performance of the power supply management system is evaluated, the system should detect the shorted circuit and turn xe2x80x9coff.xe2x80x9d Once the short is removed, the power management system should turn xe2x80x9conxe2x80x9d again, and the system should start up, undamaged.
In general, one of two physical arrangements relative to the operating system chassis is selected for performing the short circuit test. That is, the power supply may be tested using a short circuit generating device which is either positioned outside the system application chassis (external arrangement), or inside the system application chassis (internal arrangement).
In the external arrangement the short circuit generating device is typically connected to the power supply to be tested using thick cables. Typically, the short circuit generating device is positioned some distance from the system application housing. In this way the power supply may be shorted by connecting the thick cables together, and to a grounding potential, or by providing a high voltage impulse signal to the power system to force the power supply into short circuit state.
However, the exterior arrangement for performing the short circuit test is somewhat problematic in that the cables must be extremely thick in order to provide a low enough resistance for the power supply to interpret the signal provided by the cables as a short circuit. Further, the relative thickness of the cables, in turn, tends to make using the external arrangement to short a power supply extremely cumbersome. Further still, the switching of large currents in long thick cables may interfere with other test being formed simultaneously, such as, by creating an artificially generated electromagnetic field.
In an interior arrangement a short circuit generation device is mounted inside the system application chassis where the device is connected to the power management supply system. Further, wires from the short circuit generation device are generally lead outside the chassis to a remote supervisory location, where the shorting process may be controlled.
However, in order to apply a short to the power supply in the interior arrangement, a switching device typically must be used (e.g., a FET, SCR, or relay). In general, the switching devices commonly used in the interior arrangement require additional power in order to properly operate. Consequently, additional power above and beyond that necessary to run the system application must be added to the interior arrangement in order to compensate for the power necessary to operate the switching device. Also, since the power supplying the switching device typically must be maintained for the duration of the test, it cannot be drawn directly from the power supply under test.
One suggestion for solving the problem of providing the added power in the internal arrangement involves utilizing a battery to power the internal switching device. As noted previously, however, the environment in which the short circuit test is performed is often very restrictive. For instance, the computer chassis may be inside an oven, undergoing temperature testing, or in a special chamber undergoing monitoring for electromagnetic interference. Consequently, it is undesirable to use an interior arrangement powered by a battery, since the testing environment in which the battery must operate often includes extreme effects of heat, chemicals, vibration, and shock, none of which can be withstood easily by the battery. Therefore, the interior arrangement generally must draw power from an external source, which leaves the interior arrangement open to many of the same problems experienced by the exterior arrangement (e.g., noise and electromagnetic interference).
Therefore, it is desirable for a short circuit generation device to be self-powered or powered using existing circuitry, so that it may avoid the problems inherent in both the exterior and interior arrangement short circuit testing systems.
Another concern which arises in conventional power supply test methods involves ensuring that the results measured from test to test, or from power supply to power supply are reached consistently, such that, the results may be compared with relative confidence. Typically, where a power source has undergone repeated testing under similar test conditions, the test results will be remarkably different. This is because conventional testing methods generally produce inconsistent short circuits resulting from short circuit generation systems which deliver inconsistent performance due to the restrictive and harsh testing environment.
Hence, a need exist for a short circuit generation system which will deliver consistent and reliable short circuit generation performance during short circuit testing.
Accordingly, presently known short circuit testing systems for computer chassis remain inadequate, particularly in their ability to accommodate the restrictive and sometimes harsh testing environment. Thus, a need exists for a short circuit testing system which is relatively resistive to the extreme environmental variations which accompany short circuit testing and which makes it possible to generate substantially similar short circuits from test to test.
The present invention provides a short circuit generation system for use in short circuit testing which addresses many of the shortcomings of the prior art. In accordance with various aspects of the present invention, an internal arrangement short circuit generation system is provided, wherein the system induces a short in the power supply of computer chassis during short circuit testing, and additionally may be powered using internal power storage circuitry. Therefore, the present invention provides a testing system that is reliable, robust, and repeatable, notwithstanding short circuit testing conditions.
In accordance with one exemplary embodiment of the invention, the short circuit generation system may be located within the housing of the power supply management system. In accordance with another aspect of the invention, the short circuit generation system may be located within the system application chassis.
In accordance with another exemplary embodiment of the invention, the short circuit generation system may comprise a task switch for manual control of test initiation.
In accordance with another exemplary embodiment of the present invention, a system is provided wherein the short circuit generation system comprises automated initiation.
In accordance with another exemplary embodiment of the invention, a short circuit generation system may be self powered during short circuit testing.
In accordance with another exemplary embodiment of the invention, a short circuit generation system is provided which may be configured to generate short circuits of varying duration.
Further, in accordance with another exemplary embodiment of the invention, a short circuit generation system is provided which may be configured to generate short circuits for varying power supply voltages.